mm: remove redundant assignment of entry

Since ptent will not be changed after previous assignment of entry, it is
not necessary to do the assignment again.

Link: http://lkml.kernel.org/r/20190708082740.21111-1-richardw.yang@linux.intel.comSigned-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1093,7 +1093,6 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 		if (unlikely(details))
 			continue;
 
-		entry = pte_to_swp_entry(ptent);
 		if (!non_swap_entry(entry))
 			rss[MM_SWAPENTS]--;
 		else if (is_migration_entry(entry)) {